| 摘要 |
A long twist drill comprises a shank and a drill body having a drill tip (16). The twist drill has a length L and an outer diameter D, and comprising cemented carbide or high speed steel substrate, and a coating comprising at least one layer (11). The quota L/D is at least 16. The twist drill has two cutting segments (18) at the tip (16), and two flutes chip. The twist drill is provided with holes for fluid opening in the tip (16). The twist drill has an axial web thinning angle GAA which is 40 to 50°. |
